1,721,100 research outputs found
Criteria for exponential dichotomy for triangular systems
No full textWe study the exponential dichotomy properties of nonautonomous systems of linear differential equations. Any such system is kinematically similar to a triangular system. Since it is easy to determine whether or not a diagonal system has an exponential dichotomy, it is important to study the relation between the exponential dichotomy properties of the triangular system and its diagonal part. Without loss of generality, we consider block upper triangular systems and study the relation with their diagonal parts. Our study addresses both bounded and unbounded systems, on the whole line and a half line. We conclude with a study of the spectral properties of bounded systems, focusing on the relation between the whole line spectrum and the half line spectra
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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